离子膜电解槽阳极阴极涂层 IEM Anode Cathode Coating

De Nora
World Leader in Electrochemical Science,
Technology and New Markets’Applications
1°UHDENORA-DENORA Chlorine Symposium Suzhou March 2008
IEM Anode and Cathode
Coating Operation
离子膜电解阴极和阳极涂层
March 08
2AGENDA
要讨论的话题Importance of Coatings.
涂层的重要性Causes of Coating Failure.
涂层失效的原因
How Maintain good coating performances all along the guaranteed life.
在寿命保证期内，如何保持好的涂层性能Measuring the Residual coating load.检测剩余的涂层
Measuring coating and membrane condition during the operation.
在电槽操作期间，检测涂层及膜的状况
A good Anode coating:
好的阳极涂层
9Keeps your plant in business, with a very flat cell voltage profile over 8 years.
可在保证期八年时间内，维持平稳的电槽电压。

A good Cathode coating:
好的阴极涂层
9Reduces hydrogen overvoltage by more than 200 mV over bare nickel.
相对于无涂层的镍，阴极涂层可降低氢过电位200mV 以上
A Bad Anode Coating:坏的阳极涂层
9Will cause a very sharp voltage increase in a short period of time up to the point where plant has to be shut down.
可在短时间内造成槽电压迅速上升，直至使电槽被迫停车A Bad Cathode coating:坏的阴极涂层
9Will cause a quick increase of the cell voltage of about 100/150 mV: every 100 mV increase is
equivalent to ~ 3% increase in power cost.
会导致槽电压快速上升100~150mV; 槽电压上升
100mV,电耗约增3%
Causes of Anode and Cathode Coating Failure 阴、阳极涂层失效的原因
6
Anode coating failure can be caused by some impurities present in the feed brine such as:
盐水中的一些杂质会导致阳极涂层失效
Fluoride: Parts per million levels in brine will strip the DSA®coatings to bare Ti in hours.
氟：盐水中ppm级的氟也会在数小时内使涂层脱落
Manganese: Will cover existing DSA®catalyst with pseudo-catalytic coating which is almost impossible to remove.
锰：会覆盖掉阳极活性涂层，形成一层伪涂层，且几乎不可能除去
Barium/Strontium/Silica: Form tenacious deposits which are very difficult to remove.
钡/锶/硅：会沉积在活性涂层表面，且很难除去
阳极涂层失效的原因
Other possible reason of anode coating failure are:
其它可能导致阳极涂层失效的因素：
Caustic back-migration:碱的反向迁移
9OH-ion back-migration through membrane scratch.
OH -离子通过膜的划伤部位反向迁移
9OH-ion back-migration through membrane pin hole.
OH -离子通过膜上的小孔反向迁移
9Tear in the membrane.
OH
-离子通过撕裂的膜反向迁移Normal coating ageing:正常的涂层的老化
9Occurs after years of anode service.使用数年后，涂层会渐渐老化9Difficult to detect.这种情况很难探测
9Requires regeneration (recoating) of the substrate or mesh replacement.必须进行重涂或换活性网
阳极涂层失效的原因
8 Cathode coating failure can be caused by:
阴极涂层的失效可能由下列原因造成：
High Fe content in the catholyte:
阴极液中含铁太高
9Fe deposition on the cathode will cause an
over coating layer that reduces the cathode
coating activity.
Fe在阴极表面沉积形成覆盖层，会导致阴极活性降低阴极涂层的失效
9
High number of plant unprotected shut down:
过多的无保护停车
9In presence of an high number of plant unprotected (no
polarizator rectifier) shut downs there is a double effect:
过多的无保护停车（无极化整流器的投用），会造成：
•Cathodic coating peel off due to reversal current
phenomena.
反向电流造成阴极涂层脱落
•Coating deactivation and substrate corrosion due to
Cl2back migration from the anodic compartment.
Cl2反向迁移到阴极室，造成阴极涂层失去活性及镍基体的腐蚀阴极涂层的失效
March 08
10 How to maintain good coating performance all along the
guaranteed life
在寿命保证期内，如何保持好的涂层性能
How to maintain good coating performance all along the guaranteed life 在寿命保证期内，如何保持好的涂层性能
March 08 11
To maintain good anodic coating performance all along the guaranteed life is necessary to stress two main aspects of the plant operation: 要在寿命保证期内，保持好的阳极涂层性能，操作中必须注意两点： Brine Purity: 盐水质量 Apart from the impurities seen before, brine quality does not effect directly the coating life but the monitoring and good maintenance of all the brine purification section will avoid the loose of efficiency of the membrane that is among the primary reasons of early anodic coating deactivation. 除了上面提到的杂质，其它杂质不会直接影响到涂层寿命，但会 降低膜的效率。

膜效率是影响阳极涂层寿命的基本因素之一


How to maintain good coating performance all along the guaranteed life 在寿命保证期内，如何保持好的涂层性能
March 08 12
Brine Purity: 盐水质量 Monitor and record any brine impurity excursions and do not over run the plant in presence of Ca, Mg, Sr and Ba pick. 监测并记录盐水中的杂质，不要让电槽在Ca、Mg、Ba、Sr 等杂质超标的情况下运行。

Recommended Brine Specs 推荐的盐水规格
Component or Impurity 成分 NaCl Concentration 盐水浓度 Temperature 温度 pH Allowable Level 允许范围 310 gpl (Typical) 250~315 allowable
允许范围250~315 g/l 一般采用310 g/l
March 08 13
Analysis Frequency 分析频率 1 per 4 hours by operator in primary brine area 4小时一次，在一次盐水 1 per 8 hours shift, recorded automated data log 1 per 8-hour operator check to verify continuous Al reading with AAL/AAH
8小时一次由操作工分析
65oC ~ 80oC As required based on electrolyzer condition Value as required for chlorine purity 2~11 allowable range
根据对氯气纯度的要求 允许范围2-11


Recommended Brine Specs (continued)
推荐的盐水规格（续）
Component 成分 Calcium plus Magnesium 钙+镁 Strontium 锶 Barium 钡 BaSO4 Na2SO4 Chlorates 氯酸盐 Allowable Level 允许范围 < 0.020 ppm < 0.40 ppm < 0.01 ppm < 0.01 ppm < 10 gpl < 14.0 gpl as ClO3Analysis Frequency 分析频率
March 08 14
1 per 8 hours by Lab (ICP) 1 per 24 hours of storage retention, by field operator 1 per day by Lab (ICP) 1 per day by Lab (ICP) 1 per day 1 per day 每天一次 每天一次
1 per week 每周一次


Recommended Brine Specs (continued)
推荐的盐水规格（续）
Component 成分 SiO2 Aluminium Iron Nickel 铁 镍 铝 Allowable Level 允许范围 < 5.0 ppm < 0.10 ppm < 0.1 ppm < 0.003 ppm 99% Light transmittance as referred to distilled water 99%透光度 < 0.30 ppm as Pb < 0.30 ppm 按铅计 < 0.04 ppm
March 08 15
Analysis Frequency 分析频率 1 per week 每周一次 1 per week 每周一次 1 per week 每周一次 1 per week 每周一次 1 per week 每周一次 1 per month 每月一次 1 per month 每月一次
Total Suspended solid 固体悬浮物 Total Heavy Metals 总重金属 Mercury 汞


Recommended Brine Specs (continued)
推荐的盐水规格（续）
Component or Impurity 成分 Chromium 铬 Fluoride 氟 Iodine 碘 Bromine 溴 Manganese 镁 Chlorine 游离氯 TOC 化学耗氧量 Allowable Level 允许范围 < 1.0 ppm < 1.0 ppm < 0.20 ppm < 30.0 ppm < 0.01 ppm < 0.1 ppm < 1.0 ppm
March 08 16
Analysis Frequency 分析频率 1 per month 每月一次 1 per month 每月一次 1 per month 每月一次 1 per month 每月一次 1 per month 每月一次 1 per month 每月一次 1 per month 每月一次


How to maintain good coating performance all along the guaranteed life
在寿命保证期内，如何保持好的涂层性能
March 08 17
Second main aspect of the plant operation to be strictly monitored in order to maintain good anodic coating performance is: 另一个对阳极涂层有着非常重要影响的因素是：
Membrane condition: 离子膜的状况 9 Avoid circumstances which lead to damages or pin holes.
避免会导致膜产生针孔的情况的出现
9 Avoid drying of membranes during shut down (strictly follow membrane supplier indication).
避免膜在停车期间变得干燥（严格按照膜供应商的要求）
9 Control Down stream operation and DP fluctuation.
控制好下游的操作，保持稳定的压差


How to maintain good coating performance all along the guaranteed life
在寿命保证期内，如何保持好的涂层性能
March 08 18
To maintain good cathodic coating performance all along the guaranteed life is necessary to strictly monitor two main aspects of the plant operation: 要在寿命保证期内保持好的阴极涂层性能，在操作过程中要严格监控 下面两点： Catholyte purity: 阴极液纯度 Fe content in the catholyte must be carefully checked and kept within the specification given by the coating supplier. 必须认真检测阴极液中的铁的含量，一定要达到电槽供应商的 要求


How to maintain good coating performance all along the guaranteed life
在寿命保证期内，如何保持好的涂层性能
Plant smooth operation: 装置的操作要平稳
March 08 19
Unprotected (no polarizator rectifier) and unexpected shut downs should be reduced for two reasons: 应尽量避免无保护停车（极化整流器没投运）和意外停车 9 Reversal current that happened during shut down may cause cathodic coating early detachment from the substrate. 停车期间的反向电流会导致阴极涂层脱落 9 Cl2 gas back migration after shut down will cause cathodic substrate corrosion and early coating peel off. 停车期间氯气的反向迁移会导致阴极基体的腐蚀及阴极涂层脱落


Measuring the Residual Coating Load
测定剩余的涂层量


Residual Coating Load 剩余涂层
March 08 21
Coating life is related to residual coating load and active site density. 涂层的寿命与涂层量及分布有关 ¾ Initial Coating load is optimized by the supplier according with the given guaranteed life. 初始涂层量由供应商根据保证寿命来确定 ¾ Residual coating load is usually in good correlation with the residual life. 剩余涂层与剩余寿命密切相关


Residual Coating Load 剩余涂层
Residual coating load evaluation can be done
剩余涂层的评估可以： At site:在现场做 9 Residual Coating analyzed with portable XRF without radio active sources 可以用无放射源的手持式X射线仪 9 SEP (Single Electrode Potential)
SEP （电极电位）
March 08 22
In Laboratory: 在实验室 9 Residual Coating analyzed with an XRF Lab machine
用实验室中的X射线分析仪
9 Electrochemical Test 电化学分析法 9 SEM (Scanning electrode microscope) 扫描电镜法 9 Special Analysis XRD X射线衍射仪法 9 Special Analysis FIB (Focus Ion Bean) 聚焦离子束法


Electrodes section status evaluation by SEM (Scanning Electron Microscope) 用扫描电镜分析电极断面
March 08 23
Coating
Ti
Section (12000X)


Electrodes surface morphology evaluation by SEM (Scanning Electron Microscope)
用扫描电镜分析电析表面状态
March 08 24
Surface morphology (6000X)


Electrodes section status evaluation by FIB (Focus Ion Beam)
用聚焦离子束法分析电极断面
March 08 25


Electrodes section status evaluation by FIB (Focus Ion Beam)
用聚焦离子束法分析电极断面
March 08 26
Coating Ti


Anode Coating residual load 剩余阳极涂层
Anode Behaviour 阳极表现
3 2.8 2.6
Pot ent i al /V NHE 电极电位 V，NHE
March 08 27
100 90
R e s i d u a l C o a t i n g/ % 剩余涂层 %
80 70 60
2.4 2.2 2 1.8 1.6 1.4 1.2 Tons of Cl2 Produced 电解生产过程
Critical 临界状态
50 40
Dangerous 危险区域 Possible structure damages 可能损坏结构
30 20 10 0


Measuring coating and membrane condition during the operation
在操作期间监测涂层及膜的状态


Measuring coating and membrane conditions March 08 29 during the operation
在操作期间监测涂层及膜的状态
The best way to check the coating and membrane conditions during the cell operation is to continuously monitor the cell Voltage during start-ups (Polarization curves) 操作期间最佳的监测涂层及膜状态的方法是在开车期间连续监测电槽 电压(极化曲线) 9 Provides good indicators of pin-hole presence in membranes
可以显示离子膜上是否有针孔存在
9 Qualitatively asses the size & track evolution over time
可定性地分析膜上针孔的大小并跟踪其随后的发展
Continuously compare the Polarization curves from varying load conditions 经常比较电流变化时电槽的极化曲线 9 Start-up 开车时的 9 Over time: Every 3-6 months 以后每3-6个月的


Linear Polarization Curve
线性极化曲线
Typical Polarization Curve 典型的极化曲线
4 Cell Voltage 槽电压 3.5 3 2.5 2 0 1 2 3 4 5
Uo
March 08 30
Slope
6
Current Density 电流密度 KA/m2


March 08
31
U0Value U0值
Indicator of the health of a cell’s coatings and membranes
反映电槽涂层与膜的健康状态
¾Increase in U o will mean coatings and membranes are
aging and deteriorating
U0的增加反映涂层及膜的退化
¾Over the life of a cell its U o will increase
电槽达到寿命后，U0值会增加
¾Premature increase in U o should be a concern
如果电槽的U0值过早地上升，要特别关注
Features of Polarization Curve
极化曲线的特性
•Slope of the curve (k)极化曲线的斜率
Flatter the better 斜率越平越好
¾If slope increases but Uo is the same, it may be the indication of the membrane aging
如果K 值增大，而U 0不变，可能表明膜的老化¾If slope remains the same and Uo increases then coatings may be aging
如是K 值不变，而U 0增大，可能是涂层性能的退化¾No easy way to differentiate anode verses cathode yet 不能确定是因为阴极还是阳极的退化
极化曲线的特性
Shift in Polarization Curve
极化曲线的变化
2
2.53
3.5
41
1.5
2
2.5
3
3.5
4
4.5
5
Current Density 电流密度 KA/m2
C e l l V o l t a g e 槽电压
Initial 初始
Membrane 膜Coating 涂层
线性极化曲线
March 08
34
22.22.42.62.833.23.43.60
1
2
3
4
5
6
7
Current Density 电流密度 KA/m2
C e l l V o l t a g e 槽电压 （V ）
Voltage Behavior of the Cell With Pin Hole Membrane
膜上有小孔时槽电压的表现
Thank You!
谢谢！。